The invention relates to a self-tapping fastener made of stainless steel having a tool access at one end and at its other end a shaft configured as a boring part, which optionally has a thread on a partial section.
There is constantly more and more demand for fasteners made of stainless steel, which can be used especially in construction, which provide sufficient strength and in addition feature optimum boring properties.
Heretofore, it has been conventionally assumed that, for fasteners made of stainless steel which must consist of an austenitic steel for reasons of strength, a boring part made of carbon steel has to be attached. However, with these appropriately hardenable boring parts there exists the disadvantage that rust formation takes place when they are left in the open. Therefore, even for esthetic reasons alone, there arose the demand to provide other possible embodiments of self-tapping fasteners.
A screw made of stainless steel has already become known (EP 0861379 B1), in which there is provided a first shaft section which includes the screw head made of austenitic steel and a second shaft section containing the screw tip made of martensitic hardenable steel with a carbon content of less than 0.01%. Such an arrangement is indeed already an advance in the direction of a completely stainless screw, but this minimal carbon content of less than 0.01% does not yet yield optimum boring properties.